SOFT TIP CATHETER
A catheter has a main portion made from an elongated tube and a soft tip that has softer flexural properties than the tube. The tip is affixed to the distal end of the tube. A reinforcement member is intermittently embedded in the body of the tube to provide kink and shear stress resistance as well as enhanced columnar strength and torque-ability to the catheter. With the flexible soft tip, the catheter is diverted when it meets an obstacle inside the patient to prevent the catheter from harming the patient. Another exemplar soft tip catheter is a one-piece elongated catheter with its distal portion selectively notched. A reinforcement member may be embedded along the length of the one-piece catheter or only along the main body portion. The notch at the distal portion may be a spiral cut or a number of ring cuts, with possibly different pitch, width and cut depth.
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The present invention relates to catheters such as regional anesthesia catheters, including epidural catheters that provide local anesthesia to a patient and more particularly an epidural catheter that has a soft tip to prevent injury to the patient when the catheter is inserted into the epidural space of the patient.
BACKGROUND OF THE INVENTIONRegional anesthetic catheters are used to convey anesthetic agent and/or medicament to the epidural space of the patient. The catheter conventionally comprises a small bore, flexible plastic tube having a tip introduced to the epidural space through a hollow metal needle that is subsequently removed.
The catheter must be sufficiently rigid to enable it to be manipulated and introduced without kinking, but also must be sufficiently flexible to enable it to be diverted, on insertion to the epidural space, without puncturing the dura, or other obstacles therein. There are disclosed in the prior art ways of softening the tip of the catheter. Once such example is disclosed in EP 0348136, assigned to a related entity of the assignee of the instant application. As disclosed in the EP '136, to achieve a soft tip, a plurality of parallel slits are provided about the patient end of the catheter so that the flexibility of the patient end of the catheter increases, and is more easily deflected if it should meet an obstruction on insertion. The slits further provide an outlet whereby medicament may be infused to the patient. The use of slits to increase the flexibility of the catheter at the patient end is also disclosed in U.S. Pat. No. 4,801,297. U.S. Pat. No. 8,206,373 discloses the use of an elongated tubular braid along the shaft of the catheter and the attachment to the braid a distal tip made of a second polymeric material.
There is a need for an improved catheter in general and a regional anesthesia catheter in particular with a soft tip whereby the flexibility of the tip of the catheter does not cause the patient end of the catheter to balloon out when it meets an obstacle as is the case with the above-discussed prior art catheters.
SUMMARY OF THE PRESENT INVENTIONThe present invention is a low cost catheter having a soft tip with a flexibility that prevents the risk of puncturing a patient's vessel, or surrounding tissues of a cavity when the catheter is inserted thereinto. The body of the catheter is designed to be strong and durable with a reinforced wall that provides kink and shear resistance and columnar strength. The material of the catheter is bio-compatible, so that the catheter is suitable for extended human use. The catheter material is also compatible with all regional anesthesia medications, so as not to affect the potency of the drug traversing through the catheter. Moreover, the catheter is adapted to be viewable under ultrasound and is compatible with magnetic resonance imaging (MRI), so that the insertion of the catheter into the patient may be guided by viewing the catheter with ultrasound. Further, the catheter is adapted to be used for a patient who is undergoing a MRI procedure.
The catheter of the instant invention is an elongated tube that has a soft tip that has flexural properties that are softer than the main body of the catheter. The soft tip may be a tubing separately formed from the main body of the catheter, and is joined to the distal end of the main body by any of a number of different methods, to be discussed infra. A reinforcement means is embedded into the wall of the catheter, at least with respect to its main body, in an intermittent fashion along the length of the catheter to provide kink and shear resistance and also high columnar strength to the catheter. As a result, the catheter has a rigidity that complements the flexibility of its soft tip. The reinforcement means may be a member that may be made of a nonmetallic material that is compatible with regional anesthesia medications and viewable under ultrasound. Such nonmetallic material may include any of a number of polymeric materials including nylon. The reinforcement member may take the form of a continuous strip or coil that forms within and along the length of at least the main body of the catheter in a spiral fashion. For certain embodiment, the reinforcement member may include continuous strands of polymeric materials and an elongated tubular braid such as that disclosed in the afore-noted U.S. Pat. No. 8,206,373, the disclosure of which is incorporated by reference herein.
The soft tip may be affixed or fixedly attached to the main body of the catheter by over molding the proximal end of the soft tip about the distal end of the catheter body, the welding of the proximal end of the soft tip to the distal end of the main body, or the bonding of the soft tip to the catheter body by any number of conventional bonding means and methods. An innovative way of affixing the soft tip to the catheter is by using a 3-D (three dimensional) printer to add, or print, the material that makes the soft tip to the distal end of the main body of the catheter. also, the soft tip may be an extension of the catheter body.
The main body of the catheter of the instant invention may have a hardness of a given durometer (XX-XX Durometer Shore D), and the soft tip may have a lower durometer than that the main body portion, i.e., the soft tip has flexural properties that are softer than the main body, so that the soft tip is adapted to flex relative to the main body, or orthogonally relative to the longitudinal axis of the catheter. The reinforcement member added to the main body enhances the pushability of the main body and prevents the catheter from kinking and shearing.
The instant invention is therefore directed to an improved catheter, comprising: an elongated tube having a circumferential wall defining at least one lumen terminating at a distal end having an opening to the lumen; at least one reinforcement means intermittently embedded in the wall of the tube to provide a high columnar strength for the tube; a tip portion having softer flexural properties than the tube affixed to the distal end of the tube; wherein the tip portion flexes relative to the tube when it comes into contact with a surface of a vessel or an obstacle in a cavity of a patient whereinto the catheter is inserted.
The instant invention is also directed to an improved catheter, comprising: an elongated tube having a circumferential wall defining at least one lumen terminating at a distal end having an opening to the lumen, a reinforcement means intermittently embedded in the wall to provide additional rigidity to the tube to enhance the pushability, or maneuverability, of the tube, a tip portion having softer flexural properties than the tube and a proximal end affixed to the distal end of the tube, the tip portion flexes relative to the tube to divert the catheter when it comes into contact with an obstacle along its path.
The improved catheter of the instant invention may be manufactured in accordance to the following method steps of: a) forming an elongated tube having a circumferential wall defining at least one lumen terminating at a distal end having an opening to the lumen; b) embedding a reinforcement means within the wall of the tube to provide rigidity and columnar strength for the tube; c) forming a tip portion having softer flexural properties than the tube; and d) affixing the tip portion to the distal end of the tube; wherein the tip portion flexes relative to the tube to divert the catheter when it comes into contact with a surface of a vessel or an obstacle in a cavity of a patient whereinto the catheter is inserted.
The present invention is moreover directed to an improved catheter comprising: an elongated tube having a main body and a distal body along a longitudinal axis, the tube having a circumferential wall formed from an elastomeric material defining at least one lumen terminating at a distal end having an opening to the lumen, the wall having an outer circumferential surface and an inner circumferential surface, at least one reinforcement member embedded in the wall along at least the length of the main body, the wall at the distal body having portions therealong selectively weakened to provide the distal body with flexural properties that are softer than the main body.
The present invention is also directed to an improved catheter comprising: an elongated tube having a main body and a distal body along a longitudinal axis, the tube having a circumferential wall formed from an elastomeric material defining at least one lumen terminating at a distal end having an opening to the lumen, the wall having an outer circumferential surface and an inner circumferential surface, at least one reinforcement member embedded in the wall of the tube, the wall at the distal body having portions of the wall therealong orthogonal to the longitudinal axis of the tube selectively weakened without cutting into the inner circumferential surface to thereby effect the distal body to have flexural properties that are softer than the main body.
The instant invention is furthermore directed to making an improved catheter comprising the steps of: a) forming an elongated tube having a main body, a distal body and a circumferential wall formed of an elastomeric material having an outer circumferential surface and an inner circumferential surface defining at least one lumen terminating at a distal end having an opening to the lumen; b) embedding at least one reinforcement member in the wall about at least the length of the main body; and c) selectively weakening portions of the wall at the distal body to effect the distal body to have flexural properties softer than the main body; wherein the distal body flexes relative to the main body to divert the catheter to a different direction when the catheter comes into contact with an obstacle as it is maneuvered within the patient.
The present invention will become apparent and the invention itself will be best understood with reference to the following description of the instant invention taken in conjunction with the accompanying drawings, wherein:
Elongated tube 4 may have a number of different sizes, including but not limited to 20 gauge that has O.D. (outside diameter) of approximately 1.05 mm and an I.D. (inside diameter) of approximately 0.55 mm. The catheter embodiment shown in
There is embedded in wall 6 of tube 4 at least one reinforcement member, shown in the
Given that the catheter of the instant invention is to be inserted to a vessel or cavity of a patient, and in particular if the catheter is an epidural catheter to be inserted through the dura and into the epidural space of a patient, the catheter has to be compatible with human use and also has to have properties that enhance its maneuverability and prevent it from kinking. The reinforcement member embedded in the body of the catheter provides columnar strength and shear resistance for the catheter as well as prevents the catheter from kinking as it is inserted into and maneuvered within the patient. So that the tube is compatible with medicaments and drugs, for example all regional anaesthesia medications, to ensure that the potency of the drug is not altered by passing through the catheter, the tube of the catheter may be made, by extrusion for example, from a number of different medicament compatible materials including nylon, PET (polyester), PU (polyurethane), PEEK (polyether ether ketone), PEKK (polyether ketone ketone), PEI (polyetherimide) and polyimide.
Additional elastomeric materials disclosed in the afore-noted U.S. Pat. No. 8,206,373 may also be used. They include, but are not limited to, polymers such as polyoxymethylene (POM), polybutylene terephthalate (PBT), polyether block ester, polyether block amide (PEBA), fluorinated ethylene propylene (FEP), polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), polyurethane, polytetrafluoroethylene (PTFE), polyamide, polyphenylene sulfide (PPS), polyphenylene oxide (PPO), polysulfone, nylon, perfluoro(propyl vinyl ether) (PFA), polyether-ester, metals, polymer/metal composites, etc., or mixtures, blends or combinations thereof. One example of a suitable polyether block ester is available under the trade name ARNITEL®, and one suitable example of a polyether block amide (PEBA) is available under the trade name PEBAX®, from ARKEMA of North America, King of Prussia, Pa. One example of a suitable polyoxymethylene (POM) is Delrin™ commercially available from Dow Chemicals.
The catheter of the embodiment in
Proximal end 26 of tubing 18 may be affixed to distal end 10 of tube 4 a number of ways, including over molding whereby the inner circumferential wall 20b at the proximal end 26 of the tubing is fitted about and affixed to the outer circumferential wall 6a at the distal end 10 of the tube. This is shown in the exemplar embodiment of
As disclosed above, elongated tube 4 may be made from a plastics material such as nylon, polyether block amide (PEBA), or a blend of the two in some embodiments, and may have a durometer in the order of about 30-100 Durometer Shore D, preferably between 50-80 Durometer Shore D. The soft tip elongated tubing 18 may also be made of a plastics material such as nylon and other similar material as the elongate tube but may have a range of approximately 0-60 Durometer Shore D, preferably between 0-30 Durometer Shore D (or 0-100 Durometer Shore A). The elongated tube and tubing of the catheter may be constructed using any appropriate technique, for example, by extrusion, a heat bonding process, molding, and the like as is conventionally known. In addition to the material noted above, the elongate tube and tip may also be made from other plastics material such as urethane, PTFE and similar plastics material suitable for medical use.
For the exemplar catheter embodiment of
The exemplar catheters shown in
Instead of winding or wrapping about lumen 50 within wall 48 of the catheter, the reinforcement member may be substituted by a plurality of reinforcers that do not have the spiral formation as shown in
For the exemplar catheter shown in
For the
As is the case with the
It should be appreciated that the continuous spiral groove or notch shown in
Alternatively, the outer circumferential surface of distal body 46 of the catheter may be shaped to taper from the junction where distal body 46 meets main body 44 to distal end 54, so that distal body 46 may be formed as a tapered cone-shaped extension that has softer flexural properties than main body 44, to thereby allow distal body 46 to flex orthogonally relative to the longitudinal axis of catheter 40, same as the earlier discussed embodiments. In the case where distal body 46 is a cone-shaped tapered extension, there may not be a need to vary the depth of the spiral groove formed at distal body 46, or the need for the reinforcement member to extend to distal body 46 of the catheter, since the distal end of the tapered cone tends to have less material than the base of the cone that starts at the junction where distal body 46 and main body 44 meet.
For the
Even though a gradually increasing depth is shown with respect to the notches from 60a to 60i, the notches may in practice be cut at various depths to selectively control the flexibility of distal body 46 along its length. Further, even through
Another variant of the patient end portion of the catheter of the instant invention is shown in
It should be appreciated that the present invention is subject to many variations, modifications and changes in detail. Thus, all matters described throughout this specification and shown in the accompanying drawings should be interpreted as illustrative only and not in a limiting sense.
Claims
1-24. (canceled)
25. A catheter, comprising an elongated tube having a main body and a distal body, the tube having a circumferential wall formed from an elastomeric material defining at least one lumen terminating at a distal end having an opening to the lumen, the wall having an outer circumferential surface and an inner circumferential surface, at least one reinforcement member embedded in the wall along at least the length of the main body, the wall at the distal body having portions therealong selectively weakened to provide the distal body with flexural properties that are softer than the main body.
26. The catheter of claim 25, wherein the one reinforcement member comprises a one piece continuous strip or coil spirally embedded along at least the length of the main body.
27. The catheter of claim 25, wherein the weakened portions of the distal body result from a continuous spiral notch cut into the wall from the outer circumferential surface along the distal body.
28. The catheter of claim 25, wherein the distal body has a flexibility relative to the main body that varies in correspondence to the amount of the material removed from the weakened portions along the distal body, so that the flexibility of the distal body relative to the main body can be selectively varied along the length of the distal body.
29. The catheter of claim 25, wherein the distal body has a distal end and a proximal end that integrally extends from the main body; and
- wherein the amount of material removed from the weakened portions along the length of the distal body is selectively varied between its proximal and distal ends to effect a flexibility for the distal body that increases from its proximal end to its distal end.
30. The catheter of claim 25, wherein there are a plurality of circumferential notches along the distal body, each of the notches having a different width than the other notches, the notches having respective increasing widths as the notches get closer to the distal end.
31. The catheter of claim 25, wherein there are a plurality of circumferential notches along the distal body, each of the notches having a different cut depth than the other notches, the notches having respective deeper cut depths as the notches get closer to the distal end.
32. The catheter of claim 25, wherein there are a plurality of circumferential notches along the distal body, each of the notches having a different width and cut depth than the other notches, the notches having respective wider widths and deeper cut depths as the notches get closer to the distal end.
33. The catheter of claim 25, wherein the one reinforcement member comprises a strip or coil of nonmetallic material compatible with regional anesthesia medications and adapted to be viewable under ultrasound embedded within the wall spirally along the tube.
34. The catheter of claim 25, wherein the one reinforcement member comprises a polymeric strip or coil spirally wrap about the inner circumferential wall of the tube within the wall.
35. The catheter of claim 25, wherein the one reinforcement member comprises a polymeric strip or coil made from any of polymeric materials including nylon, PET (polyester), PU (polyurethane), PEEK (polyether ether ketone), PEKK (polyether ketone ketone), PEI (polyetherimide) and polyimide.
36. A catheter comprising: an elongated tube having a main body and a distal body along a longitudinal axis, the tube having a circumferential wall formed from an elastomeric material defining at least one lumen terminating at a distal end having an opening to the lumen, the wall having an outer circumferential surface and an inner circumferential surface, at least one reinforcement member embedded in the wall of the tube, the wall at the distal body having portions of the wall therealong orthogonal to the longitudinal axis of the tube selectively weakened to thereby effect the distal body to have flexural properties that are softer than the main body.
37. The catheter of claim 36, wherein the one reinforcement member comprises a one piece continuous strip spirally embedded substantially along the length of the tube.
38. The catheter of claim 36, wherein the weakened portions at the distal body result from a continuous spiral notch cut into the wall from the outer circumferential surface along the distal body.
39. The catheter of claim 36, wherein the distal body has a flexibility relative to the main body that varies in correspondence to the amount of material removed from the weakened portions along the distal body, so that the flexibility of the distal body relative to the main body can be selectively varied along the length of the distal body.
40. The catheter of claim 36, wherein distal body has a distal end and a proximal end that integrally extends from the main body; and
- wherein the amount of material removed from the weakened portions along the length of the distal body increases from the proximal end to the distal end so that the flexibility of the distal body is greater at the distal end than the proximal end.
41. The catheter of claim 36, wherein the one reinforcement member comprises a strip or coil of nonmetallic material compatible with regional anesthesia medications and adapted to be viewable under ultrasound.
42. The catheter of claim 36, wherein the one reinforcement member comprises a polymeric strip or coil spirally wrap about the inner circumferential wall of the tube within the wall.
43. The catheter of claim 36, wherein the one reinforcement member is made from any of polymeric materials including nylon, PET (polyester), PU (polyurethane), PEEK (polyether ether ketone), PEKK (polyether ketone ketone), PEI (polyetherimide) and polyimide.
44. The catheter of claim 36, wherein the one reinforcement member is not embedded in the distal body; and
- wherein there are a plurality of circumferential notches along the distal body, each of the notches having a different width than the other notches, the notches having respective widths that increase toward the distal end of the distal body.
45. The catheter of claim 36, wherein the one reinforcement member is not embedded in the distal body; and
- wherein there are a plurality of circumferential notches along the distal body, each of the notches having a different cut depth than the other notches, the notches having respective cut depths that increases toward the distal end of the distal body.
46. The catheter of claim 36, wherein the one reenforcement member is not embedded in the distal body; and
- wherein there are a plurality of circumferential notches along the distal body, each of the notches having a different width and cut depth than the other notches, the respective widths and cut depths for the each notch being greater as the each notch gets closer toward the distal end of the distal body.
47. A method of making a catheter, comprising the steps of:
- a) forming an elongated tube having a main body, a distal body and a circumferential wall formed of an elastomeric material having an outer circumferential surface and an inner circumferential surface defining at least one lumen terminating at a distal end having an opening to the lumen;
- b) embedding at least one reinforcement member in the wall about at least the length of the main body; and
- c) selectively weakening portions of the wall at the distal body to effect the distal body to have flexural properties that are softer than the main body;
- wherein the distal body flexes relative to the main body to divert the catheter to a different direction when the distal body comes into contact with an obstacle as the catheter is maneuvered within the patient.
48. The method of claim 47, wherein the step c comprises the step of effecting a continuous spiral notch cut from the outer circumferential surface into the wall at the distal body to provide the weakened portions.
49. The method of claim 47, wherein step c comprises the step of:
- varying the amount of the material removed from the weakened portions along the distal body to selectively adjust the flexibility along the distal body relative to the main body.
50. The method of claim 47, further comprising the step of:
- forming the one reinforcement member as a strip or coil of nonmetallic material compatible with regional anesthesia medications and adapted to be viewable under ultrasound.
51. The method of claim 47, further comprising the step of:
- forming the one reinforcement member from any of polymeric materials including EPTFE (expanded polytetrafluoroethylene), nylon, PU (polyurethane), polyurethane PET, PEEK (polyether ether ketone), PEKK (polyether ketone ketone), PEI (polyetherimide) and polyimide.
52. The method of claim 47, wherein the step c further comprises the steps of:
- forming a plurality of circumferential notches along the distal body; and
- forming each of the notches to have a different width than the other notches; and
- increasing the respective widths of the notches as the notches get closer to the distal end.
53. The method of claim 47, wherein the step c further comprises the steps of:
- forming a plurality of circumferential notches along the distal body;
- forming each of the notches to have a different cut depth than the other notches;
- increasing the depth of the respective notches as the notches get closer to the distal end.
54. The method of claim 47, wherein the step c comprises the steps of:
- forming a plurality of circumferential notches along the distal body;
- forming each of the notches to have a different width and cut depth than the other notches; and
- increasing the respective widths and cut depths for the notches as the notches get closer to the distal end.
Type: Application
Filed: Dec 12, 2014
Publication Date: Jun 25, 2015
Applicant: SMITHS MEDICAL ASD, INC. (Rockland, MA)
Inventors: J. Michael Kennelly (Keene, NH), Geoff Clark (Lempster, NH)
Application Number: 14/568,184